<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <link rel="stylesheet" href="my.css">
    <style>
        /*id选择器*/
        #p1 {
            color: red;
        }

        /*类选择器*/
        .c1 {
            color: yellow;
        }
        /*分组选择器*/
        h4,#p1,.c1{
            background-color: yellow;
        }
        /*属性选择器*/
        input[type="text"] {
            color: orange;
        }
        /*任意元素选择器*/
        /*边框:粗细 样式 颜色*/
        *{
            border: 1px solid green;
        }
    </style>
</head>
<body>
<input type="text">
<input type="password">
<p id="p1">苹果</p>
<p class="c1">香蕉</p>
<p id="p3">橘子</p>
<h3 class="c1">洗衣机</h3>
<h3>冰箱</h3>
<h3>电视机</h3>
</body>
</html>